Clean energy transition and climate vulnerabilities: A comparative analysis of European and non-European developed countries

Currently, the world faces an existential threat of climate change, and every government across the globe is trying to come up with strategies to tackle the severity of climate change in every way possible. To this end, the use of clean energy rather than fossil fuel energy sources is critical, as it can reduce greenhouse gas emissions and pave the way for carbon neutrality. This study examines the impact of the energy cleanability gap on four different climate vulnerabilities, such as ecosystem, food, health, and housing vulnerabilities, considering 47 European and non-European high-income countries. The study considers samples from 2002 to 2019. This study precedes the empirical analysis in the context of a quadratic relationship between the energy cleanability gap and climate vulnerability. The study uses system-generalized methods of the moment as the main technique, while panel quantile regression is a robustness analysis. Fixed effect and random effect models have also been incorporated. The study finds that the energy cleanability gap and all four climate vulnerabilities demonstrate a U-shaped relationship in both European and non-European countries, implying that when the energy cleanability gap increases, climate vulnerability decreases, but after reaching a certain threshold, it starts to increase. Development expenditure is found to be negatively affecting food and health vulnerabilities in European nations, while it increases food vulnerability and decreases health vulnerability in non-European nations. Regarding industrialization’s impact on climate vulnerabilities, the study finds opposite effects for the European and non-European economies. On the other hand, for both groups, trade openness decreases climate vulnerabilities. Based on these results, the study recommends speeding up the energy transition process from fossil fuel energy resources towards clean energy resources to obtain carbon neutrality in both European and non-European groups.


Introduction
The world is facing economic sustainability challenges in the era of rising temperatures up to 3˚C.This rising temperature directly affects an environment and ecosystem's biological, chemical, and physical distinctiveness [1].Furthermore, the rising temperature has adverse outcomes for the ecosystem and the health of human beings since the survival of human beings depends critically on the planet's environment [2].The average heat wave has increased by 0.08˚C per decade since 1860, rainfall has decreased by about 0.4%, and soil breakdown has increased by 0.8%.From 1901 to 2015, the worldwide sea level rose by about 19.5 cm and observed a 1.7 mm expansion in sea level each year [1].Alarmingly, changes in oceans caused by rising temperatures could rapidly affect ecosystems.The sea level has risen more than the predicted upper limit of sea level rise since 2000.Furthermore, climate vulnerabilities are increasing the acidification of the atmosphere.This acidification process is disturbing the ozone layer, and the pH level of the oceans is changing, resulting in a very alarming situation.In addition, global warming is increasing economic losses through flooding and coastal erosion.This is causing sea level rise, and rapid adaptation techniques are needed to address this issue [1].The contributing factors to climate vulnerabilities have been primarily attributed to the extraction of fossil fuel resources, which are depleting over time.From this point of view, the study in [3] pointed out that countries need to work hard to solve problems related to environmental and economic development.However, industrialization and the globalization process are also considered to be responsible for environmental deterioration.
Non-renewable energy sources have been crucial components for the growth of an economy for many years, but CO 2 emissions are linked with the growth as well.In addition, many factors, including economic activity, technological innovation, and the cost and effectiveness of environmental protection, affect a country's environment [4].Particularly, using fossil energy is linked to ecosystem vulnerability, and the impacts have increased by 150% since 1970.However, unexpected climate alterations have recently increased worldwide temperatures.Compared to the end of the last ice age, CO 2 emissions have increased by 100 times faster, as per a report by the National Oceanic and Atmospheric Administration.In this view, the consumption of coal, gases, and oil is an input to electricity-generating companies that are the primary source of CO 2 emissions.These emissions, along with black carbon, are catching the temperature of the sun and heating this planet.Regardless, recent climate changes pose threats to the continuity of natural ecosystems.
Furthermore, fossil fuel sources are depleting the oxygen levels in the ecosystem and increasing food threats to the world.As noted in a report by the International Union for Conservation of Nature, low oxygen levels only affected 45 sites in the early 1960s [1].However, it reached more than 700 locations worldwide in 2020.In this regard, fossil energy is empirically blamed for oxygen loss.Furthermore, food and health vulnerabilities are the critical outcomes of carbon-omitted fuel.Additionally, unexpected changes in the atmosphere and droughts have started food supply shortages in several world regions.Notably, less developed and developing countries are particularly vulnerable to climate change and its extremes, such as drought [5].In this view, different studies have projected that 60% of other foods might be required worldwide, and in low-income countries, food demand will rise by 100% until 2050 [1].Likewise, a sustainable climate is particularly important to secure food chains and improve trade markets.The improper handling of waste materials also contributes to increased climate vulnerability.According to this perspective, the research by [6] emphasizes how the creation of waste recycling systems has compelled households in European nations to switch to renewable energy sources.This process has enabled countries to generate more green energy through waste recycling.
Also, these climate vulnerabilities pose a significant threat to the natural habitats of organisms along the lines of ecosystem, food, habitat and, health vulnerabilities.Commonly, climate vulnerabilities are linked with traditional energy inputs, which are causing the worldwide temperature to rise, and further, melting glaciers are leading to floods and intensifying sea levels over time.Undoubtedly, climate risks cannot be separated from economic development.Atmospheric changes also put more pressure on health vulnerabilities.While it is true that developing countries are more prone to the effects of climatic changes, developed countries have also been facing these challenges [7].Rising sea altitudes, heat, and increasing flood events are blamed for economic damage and high death rates.Landslides, debris flows, and floods cause hundreds of deaths, billions of dollars worth of property damage, expensive infrastructure, and the destruction of a large amount of the region's limited arable area each year [8].These problems are closely related to the economic structure of developed countries.Particularly throughout the 1980s, developed economies accounted for 60% of world GDP, but shares of the population were just 14%.In the meantime, developed economies have approximately 85 percent of the world's GDP and 1/3 of the global population.In the 1990s, these top twenty economies accounted for over half of GHG emissions.Emissions from European advanced economies have declined recently, but non-European advanced economies have maintained their carbon emissions.
The study focuses on European and non-European high-income countries.The selection of countries and the comparative analysis make this study unique from other studies.The study found that European countries are showing keen interest in clean energy for environmental sustainability as compared to other developed countries.Since 1990, the European Environment Agency (EEA) has shown particular interest and helped format policies for creating a sustainable environment on the European level.The differences in environmental degradation in different parts of the world are visible.Since the 1990s, the EEA has supported the development and implementation of environmental policies, educated the public on environmental issues, incorporated environmental concerns into policy areas, and focused on ecological themes for three decades.These efforts are intended to advance environmental knowledge and action, but their effects have not yet been fully assessed because significant changes take time.However, non-European countries' intentions to mitigate climate risks are still unclear as their policy continues to be concentrated around fossil energy sources.Furthermore, the energy patterns of non-European countries need to be more compatible with people's environmental knowledge and risk perception.Because understanding the vulnerability of climate risks leads to a more sustainable attitude toward energy consumption, this understanding of sustainable behavior can be borrowed from European countries.
In addition, the Paris Agreement was a major international effort to combat climate change, pledging that temperatures should drop by about 2˚C.According to this perspective, energy intensity and structure are crucial [9].However, non-European developed countries did not accelerate their actions at the desired pace [10].Investing in and adopting clean energy can help mitigate climate change.Clean energy played a key role in meeting the Kyoto Protocol agreement, where most European economies dedicated their efforts to reducing climate risks and succeeded in reducing greenhouse gases by 8% in 2012.In particular, the European Environmental Agency reported that, despite promoting economic growth, the EU has reduced net greenhouse gas emissions by 31% since 1990, including from international aviation.Energy supply and transportation increased in the wake of rising natural gas prices [11].Various economies have designedclean energy strategies to cut GHG and adjust manufacturing procedures for climate change abatementbecause they can improve the efficiency of resources and their conservation and pave the way toward a green economy.In these strategies, energy cleanability is prominent in reducing climate vulnerability, such as ecosystem, health, habitat, and food vulnerability.
Owing to the above discussion, this study makes several contributions to the empirical literature.Firstly, as far as the authors are aware, this is one of the few empirical studies that looks at how the shift to clean energy affects climate vulnerabilities.Having access to energy is one of the crucial components of economic development and social welfare.However, there is a significant gap in this area around the world, as a large number of populations do not have reliable or clean energy access.However, the world has begun to show interest in both economic and sustainable environments [3].This study distinguishes itself from other studies by looking at the effects of the clean energy transition on four types of climate vulnerabilities, such as ecosystem vulnerability, food vulnerability, health vulnerability and, habitat vulnerability.The study introduces a new energy cleanability gap through the use of the entropy weights method.Moreover, the study includes the square of the energy cleanability gap to see if the relationship between clean energy transition and climate vulnerabilities is U-shaped or inverted U-shaped.
To this end, the first research question of the study can be formulated as follows: Research Hypothesis 1: Does the relationship between clean energy transition and different forms of climate vulnerabilityexhibit a non-linear pattern?
Second, this study contributes to the empirical literature by dividing the sample into European and non-European high-income or developed countries.This distinction is important as it can identify the contributions of the clean energy transition to food, habitat, ecosystem and health vulnerabilities separately for two groups.Therefore, the second research hypothesis can be formed as follows: Research Hypothesis 2: Does the effect of the clean energy transition differ between European and non-developed economies?
Third, the study includes several additional independent variables, such as development expenditure, trade openness, and industrialization.These variables can significantly influence climate vulnerabilities, and their effects may also differ across food, health, habitat, and, ecosystem vulnerabilities, as has been demonstrated in the empirical literature.Therefore, the third research hypothesis can be formed as follows: Research Hypothesis 3: Do the effects of development expenditure, trade openness, and industrialization differ across the four forms of climate vulnerability?
Fourth, this study also contributes by using novel methodologies.In addition to using fixed effects and random effects, this study relies on the system generalized method of the moment method as well as the panel quantile method.The advantage of system GMM over other methods such as fixed effects and random effects is that this method can take care of any endogeneity issue inherent in the model.However, this study also includes the panel quantile method to see if the effects of independent variables on dependent variables differ across quantiles.
Fifth, the results of the study provide several policy implications that can be used by other developed countries around the world to formulate their climate and energy policies.From the results, it has been demonstrated that the relationship between clean energy transitions and climate vulnerabilities is U-shaped.It implies that at the beginning stage, when the energy cleanability gap increases, the different forms of climate vulnerabilities start to decrease; however, after reaching a certain threshold, climate vulnerabilities increase with a further increase in the energy cleanability gap.Subsequently, in addition to the clean energy gap, this study finds that development spending decreases the vulnerability of ecosystems, food, and health insecurity in Europe while increasing ecosystem vulnerability and reducing health vulnerability in non-European nations.Additionally, this study also exhibits that industrialization can improve ecosystems, food, and habitat in European countries, while in non-European nations, infrastructure increases ecosystem, habitat, and health risks.The current study also reveals that trade openness improves climate and food security in developed European countries.In contrast, in non-European developed countries, the effects of trade openness on food, habitat, and health vulnerabilities are negative and positive for ecosystem vulnerability.The policy approach requires countries to clean up their energy patterns to maintain sustainable conditions.
Finally, this study has been arranged as follows: The literature of earlier studies is given in Section 2, the methods and analyses are explained in Section 3, the results are presented in Sections 4 and 5, which include a discussion, and in Section 6, the conclusion and future research are discussed.

Empirical literature review
Climate vulnerability and the consequent more frequent extreme events are expected to affect the function and structure of ecosystems.In this view, prior studies have proposed that famine is the most significant trauma to the ecosystem's vulnerability.The study by [12] defines ecosystems as complex, open systems consisting primarily of social, natural, and social-naturally interconnected systems.In particular, ecosystem vulnerability refers to the sensitivity and resilience of ecosystems to external disturbances.This vulnerability has become widespread worldwide [13].Further, ecosystem vulnerability and renewable energy assessment [1] results indicate that energy cleanability is an encouraging and significant factor in reducing climate change.It can help decrease temperature and CO 2 emissions in the atmosphere, moderating the ecosystem, which can be readily done using clean energy.
Furthermore, the study scrutinized the environment-centric policy on clean energy changes.Their finding indicates that developed economies have observed low GHG emissions compared to developing economies.In addition, ecosystems and food vulnerability have emerged as two of the most challenging issues.The Rio Conference and Brundtland Report highlighted the importance of each economic action for securing worldwide sustainability improvement [14].Seventy percent of the global population is expected to live in urban areas by 2050; this urbanization should be accommodated with modernization to promote clean energy systems.As a result of unexpected climate changes, it is also expected that there will be food vulnerability in many regions of the world.
Clean energy is carbon-unbiased, and numerous other economies have taken advantage of renewable energy sources to attempt climate transformation for the better.However, this change includes a lot of restrictions and has found social and political obstacles to promoting renewable energy resources for sustainable progress.Furthermore, their study urged for a clean energy program in the energy sector of low-income countries.The macroeconomic impact of clean energy on the ecosystem vulnerability of overall high-income economies found that energy cleanability reduced the negative impact on the climate by diminishing fossil energy emissions.Furthermore, their study pointed out the impact of trade on habitat vulnerability to climate change; they pointed out that development expenditures and trade openness reduce health, habitat, food, and ecosystem vulnerability.Finally, the outcomes showed that an augmented share of energy cleanability leads to decreased chances of temperature variation.
The prior studies presented a connection between energy cleanability and climate risks.Studies observed a nonlinear link between clean energy and environmental degradation by creating the capability to handle climate variation risk.So when there is a clean energy transition, there is a massive infrastructure installation expense and a conventional infrastructure dismantling cost.As a result, such a transition in energy system optimization is needed to reduce health, food, and ecosystem vulnerabilities by regulating the energy cleanability range.
Moving from fossil fuels to new and renewable technologies is necessary for the upcoming global energy transition, which raises the need for associated materials.To supply renewable energy for transportation sectors, the study in [15] looks at the long-term availability of materials used in the energy transition.In particular, it is a significant factor in the increasing demand for rechargeable batteries.This study demonstrates the importance of rechargeable materials in achieving a sustainable energy transition.Furthermore, the presence of well-established recycling systems, the realization of vehicle-to-grid integration, and the development of transportation services with reduced material intensity are necessary to attain a balanced supply and demand throughout this century.Consequently, it is crucial to implement a coordinated worldwide effort to carry out a variety of policy objectives for a sustainable energy transition.
In addition, ecosystem vulnerability can be decreased via energy.The IPCC defines ecosystem vulnerability with more sensitivity, and fragile adaptation would produce a vulnerable structure [16].Transformation evaluates an ecosystem's capability to address climate vulnerability and reasonable possible loss and uphold a stable system.The degree to which a design exaggerates climate vulnerability is known as sensitivity.Further, minimizing such exposure to food in agricultural production is required to keep millions of people alive, and it can be done by reducing the fuel emissions associated with fossil sources [17].
The study in [18] examines how renewable energy policy addresses energy equity and vulnerability.Their study showed that respondents who are low-income, non-white, and renters are more vulnerable to energy shortages than other groups.In particular, non-white respondents were seven times more likely than white respondents to report being without heat, while low-income and renter respondents were nearly three times as likely to do so.Although household transition benefits are not distributed relatively under existing rules, this vulnerability exists despite the state's reputation as a leader in renewable energy.Their findings further indicate that renters were three times more likely than homeowners to report having solar panels, and non-white respondents were seven times less likely than white respondents to report having them.Household transition benefits are predominantly accessible to high-income households, according to interviews.Their study contends that policies that distribute transition benefits to households with discretionary money, property rights, and institutional discrimination may be to blame for these differences.Therefore, it is required to provide substitute frameworks for policymaking that place justice at the center of the energy transition process, which is an anti-resilience framework.
The UK must make significant investments in low-carbon energy infrastructure to meet its net-zero emissions objective.The so-called green finance gap results from investors' insufficient present investments in renewable energy capacity.However, current energy economy models typically obscure the macroeconomic effects of policies meant to increase green financing for energy transitions.Taking into account the aforementioned [19], expands on the energy-economy Green Investment Barrier Model to examine the macroeconomic effects of a scenario in which policies intended to close the green finance gap are implemented, both in tandem with and apart from a strategy to decarbonize the power sector.This study does this by incorporating the insights from a systematic literature review into the model.Their study also contrasts the outcomes with research addressing a related research subject.Their study concludes that a policy scenario that closes the green financing gap with a low-carbon power projection results in lower power system costs, reduced unemployment, and a higher GDP.
Governments all around the globe must engage citizens to strengthen policy legitimacy and guarantee successful energy transitions as a result of a global reduction in public confidence.It is commonly believed that deliberate policymaking, an advanced type of participatory policymaking that emphasizes communication and debate, may increase trust and, as a result, the legitimacy of policies relating to energy transitions.However, deliberative policymaking's potential and constraints are still up for dispute.The study of [20] adds to this discussion by examining deliberative policymaking from a trust standpoint.Their study provides a trust-based systems framework for deliberative policymaking in energy transitions.Their research methodology is examined and used in a case study of a 2012 Japanese national deliberative poll on energy.The results show that a trust gap may compromise the efficacy of deliberative procedures in which increased policy legitimacy is seen as a goal and public engagement is valued as input.Their research demonstrates the complexity of the trust gap, which has three components-confidence in information, motivations, and competence-and three different forms of directional dynamics (vertical, horizontal, and temporal).Additionally, their analysis highlights two crucial contextual factors that may prevent the closing of the trust gap: the general political climate and the context of widespread mistrust.
According to [21] findings, renewable energy can reduce carbon emissions and significantly increase environmental degradation in G7 countries.Furthermore, they also found the validity of the EKC hypothesis.A study by [22] pointed out that clean energy harms climate risk.Moreover [23], found that clean energy and climate are negatively correlated across across newly industrialized countries.Regarding energy consumption and trade [24], found that energy consumption increases emissions, while globalization reduces CO 2 in G7 nations and increases it in E7 nations.However, the study by [25] shows opposite results and shows that trade opennessis causing an increase in climate risk in Turkey.For OECD economies [26], discovered that renewable energy mitigates environmental deterioration.
The study of [27] highlights extreme weather events such as heat waves, hurricanes, flooding, and droughts, as well as the increasing quantity of scientific data connecting these occurrences to human-caused climate change.Due to its shared vulnerability to these climaterelated risks, Cameroon has set aside the integration of 25% renewable energy in its energy production mix and a 32% emission reduction.However, the new obligations and Cameroon's fast-expanding energy needs have opened the door for a new energy production method.Their paper investigates how a more sustainable energy transition that provides practical options for emission reduction while avoiding high-carbon paths might help to meet these emission reduction objectives.After using the Low Emissions Analysis Platform tool and a back-casting methodology, their analysis found a gap between designated policy goals and current actions in terms of execution.

Research gap
From the literature discussed above, there seems to be extensive literature on the relationship between renewable and non-renewable energy sources and emissions of greenhouse gases or environmental sustainability.However, apart from this aspect, the literature lacks new research on food, ecosystems, health, and habitat's environmental dimensions.This study introduces novelty to the literature by introducing the effects of energy on ecosystems, food, health, and habitat security, which have not been explored in previous studies.This study is unique in the sense that it introduces an energy cleanability gap via the entropy weights method, which can explain the lack of clean energy in a country.Moreover, the study makes a novel attempt to see if there is a non-linear relationship between the clean energy gap and climate vulnerability.The study considers developed or high-income countries and makes a comprehensive comparative analysis between two groups of European and non-European nations to see if the impact of the clean energy gap on climate vulnerability differs by region.To the best of these authors' knowledge, no studies have yet investigated this issue for such sample groups.Moreover, the study uses both the system GMM method to take care of the endogeneity issue and the panel quantile method to see how the results differ across higher, medium, or lower quantiles.

Theoretical framework
This study provides an exploration of the climate vulnerabilities in European and non-European developed countries, focusing on the energy cleanability gap, development expenditure, industrialization, and trade openness.Energy is critical to both economic development and climate vulnerability.In European and non-European developed countries, a large part of their economic expansion comes from the use of fossil fuels.The abundance of natural resources provided these economies with an added advantage to accelerate economic expansion, in addition to other factors.As the economies of these countries developed and their living standards improved, the average age of the population began to increase.However, as these nations have developed based on fossil fuels, carbon emissions are hurting climate vulnerabilities.The energy demand of the industrial sector is increasing due to globalization, and current energy development is insufficient to reduce emissions at this level.As such, there is a need to shift the energy patterns of these countries toward clean energy sources to reduce emissions and minimize climate vulnerabilities.Therefore, it can be expected that energy cleanability will have a significant impact on environmental sustainability in European and non-European developed countries.The relationship between climate vulnerabilities and the energy cleanability gap is based on the fact that there is a nonlinear relationship between them.This study hypothesizes that an increase in the clean energy gap first decreases climate vulnerability, but after eventually reaching a tipping point, it reduces climate vulnerability.Hence, the relationship between the clean energy gap and climate vulnerability is U-shaped.
To address the climate crisis, the United Nations initiated the Sustainable Development Goals (SDGs) in 2016, which were agreed upon all member nations.A collective effort and green financing are essential for low carbon emissions [28].However, even after setting the SDGs for 2030, the focus is on "simple development" rather than "sustainable development" in industrialized and developing countries.Likewise, this may be the primary justification for maintaining lax national regulations to create a soft legal framework that attracts foreign capital.Such an adaptive framework has accelerated development expenditure and increased the amount of industrial growth, but at the cost of the health of the local population and the environment.Generally, government expenditure may have both direct and indirect effects on the quality of the environment.
Furthermore, studies such as [29] have explained how industrial growth raises energy consumption in host nations by promoting the growth of transportation, industry, and the manufacturing sector.The impact of industrial growth on energy consumption is evident in most countries, and the findings demonstrate that industrial growth is a major cause of high energy consumption.However, there is still much debate on how industrial growth affects carbon emissions in both industrialized and developing nations.Analyzing how industrial growth affects the environmental sustainability gap is important.Because it makes it possible to assess the damage that industrial growth causes.The recent health crisis of COVID-19 and the China-US trade war have put the economic outlook of the world in a gloomy position.Therefore, worldwide trade policies and markets are now uncertain about reviving the relationship between the environment and trade, and at the same time, this relationship has become even more significant and firm for nations that want to open their economies [24].Furthermore, trade openness can intensify the problems of urbanization and industrialization and cause deterioration of the natural environment.Therefore, trade openness is considered to negatively affect the environmental sustainability of European and non-European developed countries.

Data and variable description
With the inclusion of the energy cleanability gap and its square, development expenditure, industrialization, and trade openness, the study considers the following four models for four forms of climate vulnerability as dependent variables: Here, ESV indicates ecosystem vulnerability, FDV is food vulnerability, HAV is habitat vulnerability, and HEV is health vulnerability; α is a constant term; ECL is energy cleanability gap; EXP is development expenditures; IND is industrialization; TRD is trade openness; ε refers to error term; i refer to cross sections, and t is period.Table 1 provides the variable description and data source.The study introduces an energy cleanability gap index using two indicators, as mentioned in the following equations.This study constructs energy cleanability as follows: ECL is the abbreviation for Energy Cleanability Gap; ACC is Access to Clean Cooking; and SRE stands for a Share of Renewable Energy.Further, entropy weights are used, and the total weight is written as follows: The energy cleanability gap shows the lack of clean energy in a country.Subtracting ECL from 1 provides a value for the sustainable energy gap economies want to seal.ECL gives magnitude to the sustainable energy gap in a region.The following equation is then specified as follows: Furthermore, nonrenewable resources provide short-term advantages, but they have degraded the environment for a long time.In this regard, the revolution of the current energy status to renewable energy resources needs massive financing to establish clean energy plants.
The energy transition initially makes ecosystems more susceptible to climate change due to the high share of fossil fuels.Still, the growing use of renewable energy will make them less vulnerable as they mature.The energy transition to development obstruction designates that the share of energy cleanability in the total energy spectrum is still low, which follows a quadratic effect on climate vulnerabilities [30].Four life-sustaining sectors-ecosystem, habitat, food, and health-are used in the analysis to determine the impact of the energy cleanability gap.The sample of data included 47 cross-sections with heterogeneous energy cleanability levels.Data for climate vulnerability is taken from the Notre Dame Worldwide Adaptation Initiative (ND-GAIN) [31].
The current study hypothesizes that, primarily, the energy cleanability gap will increase climate vulnerability.The transition towards clean energy will decrease habitat ecosystems, health, and food vulnerability.When the energy transition's infrastructure is managed, it might be granted a more extended period of saving and improvement in food and health vulnerability, population habitat, and health.This generates an association between climate exposure and energy cleanability.
The connection between the energy cleanability gap and vulnerabilities is revealed in Fig 1 .Development expenditure is general government expenditure on education and health (current, capital, and transfers).Therefore, this study considers spending by the government on both education and health as a percentage of GDP. Trade is the sum of exports and imports of goods and services measured as a share of the gross domestic product.Industrialization refers to the value added to the industrial sector as a percentage of GDP.Data for EXP, TRD, and IND comes from the WDI database.Table 2 provides the list of countries used in the analysis.

Methodology
For the evaluation and effect of the energy cleanability gap on the vulnerabilities of food, ecosystem, habitat, and health in 47 selected economies, this paper first employs the variance inflation factor for the multicollinearity issue among the independent variables and descriptive statistics.A flow chart of the methodologies used is presented in Table 3.
In the case of more cross-sections, dynamic panel data is more suitable for tackling heteroskedasticity and serial correlation issues.Moreover, there might be endogeneity, which can arise from reverse causality or missing variables [32].For example, climate vulnerabilities may have reverse effects on the clean energy gap, and this can produce endogeneity that needs to be tackled.Therefore, the study chose theSystem Generalized Methods of Moment(GMM) method by [33,34]which can take care of this estimation issue.Furthermore, the study employs panel quantile regression, which the system GMM method is unable to provide, to investigate the effects of independent variables on the dependent variable at different quantiles [32].

Results
The study starts with the descriptive statistics listed in Table 4.According to the descriptive statistics, TRD has the highest mean among the European nations, followed by IND and EXP.This is also true for non-European high-income countries.Comparing the European and non-European developed nations, it can be seen that the highest trade openness is in European nations, while non-European nations have the highest industrialization rate.In terms of climate vulnerabilities, non-European countries have the highest levels of food, habitat,  5.
According to the thumb rule of VIF, the coefficient value of VIF must be under 10 to reject the null hypothesis of multicollinearity among the variables [32].As the coefficient value is well below the above-mentioned critical bound; therefore, null hypothesis can be rejected and the alternative hypothesis of no multicollinearity among the model parameters is evident for both European and non-European high-income economies.Thus, under-consideration parameters are unconnected from each other.Table 6 shows the results of fixed effect, random effect and GMM.
Based on the above data, the study applied Generalized Methods of Moment (GMM) for its efficiency in handling the issues mentioned earlier.Furthermore, both a fixed effect model and a random effect model have been utilized in this study.The Housman test yields significant results and favors the fixed effect model in this regard.However, a random effect model is preferred in the ecosystem vulnerability model of non-European countries.However, further Considering all these backgrounds, this study used the Generalized Methods of Moment (GMM) to examine the long-run empirical relationship in all selected models.The estimated GMM model outcomes are presented in Table 6.The long-run linkages unveiled the pattern of energy clean ability gap (ECL) or clean energy gap and climate vulnerabilities (ecosystem (ESV), food (FDV), health (HEV), and habitat (HAV).This study finds that the impact of the current level of ECL on these vulnerabilities is negative and statistically significant for all selected climate vulnerabilities.Additionally, in European nations, a one-unit increase in ECL can lead to corresponding decreases of 0.36, 0.25, 0.04, and 0.64 units in FDV, HEV, HAV, and ESV.Furthermore, favorable and statistically significant effects on climate vulnerabilities are shown in the selected countries by the energy cleanability gap's (ECL 2 ) quadratic effect on these vulnerabilities, namely, ESV, FDV, HEV, and HAV.In particular, the empirical finding showed that 1 unit of ECL 2 expands ESV, FDV, HEV, and HAV by 0.37, 0.40, 0.95, and 0.89 units, respectively.Notably, the results of ECL and ECL 2 are also consistent with non-European developed countries.In addition, the plots provide more in-depth analysis as the quadratic effect of ECL on selected climate vulnerabilities confirms the U-shaped relationship in developed countries under this study.These relationships are plotted in Fig 2.
The development expenditure shows an insignificant impact on ecosystems and habitat vulnerability in European countries.As far as the significant results matter, a 1% increase in development expenditure causes a 0.15% and 0.13% reduction in food and health vulnerability, respectively.However, in non-European countries, development expenditure shows some contrasting results with European countries, and it has shown a significant impact on ecosystem vulnerability.Moreover, industrialization has a significant effect on climate vulnerabilities in European countries.Echoes of contrasting outcomes from European and non-European panels become more apparent in this study as Europe's industrialization hurts ecosystem, food, and habitat vulnerabilities.In particular, a 1% increase in industrialization decreases ecosystems, food, and habitat by 0.15%, 0.15%, and 0.26%, respectively.Non-European developed countries show a positive relationship between development expenditure and ecosystem, habitat, and health vulnerabilities.A 1% increase in industrialization increases ecosystem, habitat, and health vulnerabilities by 0.15%, 0.26%, and 0.13%, respectively.Lastly, trade liberalization has shown a negative relationship with climate vulnerabilities.Specifically, a 1% increase in trade openness has reduced ecosystem and food vulnerability by 0.23% and 0.25, respectively, in European countries.However, other non-European developed countries have inconsistency in results as it has a positive impact on ecosystem vulnerability.
Here, to give a comprehensive explanation, this study report five quantiles ði:e:; 05th . . . . . .; 95thÞ during the PQR regression process as robustness analysis (See Table 7).Specifically, taking into account the ecosystem vulnerability (ESV), energy cleanability gap, and its square support the Generalized Methods of Moment outcomes and are consistent with their impact and relationship.However, development expenditure (EXP), industrialization (IND), and trade openness (TRD) effects on ESV are incompatible with earlier generalized methods of moment outcomes.
In particular, the quantile results of EXP show only significant negative signs in the 75 th to 95 th quantiles, respectively.Thus, in 25% quantiles, it remains significant, and the study of [35] pointed out that these countries showed more interest in adopting environment-friendly technologies.Furthermore, IND also showed inconsistency in the initial to 25th quantiles, but after that, it became consistent with earlier GMM outcomes.Moreover, TRD outcomes are consistent with earlier mean regression results except for initial quantiles, where it remains insignificant.However, considering the non-European developed countries panel, it shows inconsistency in EXP for the last quantile.Additionally, considering the food vulnerability (FDV) panel, all variables depict consistency with GMM outcomes in all quantiles.However, the non-European developed countries panel shows some inconsistency as it has inconsistent and insignificant outcomes in the initial quantiles to the 25th quantiles.Lastly, trade openness (TRD) shows inconsistency in initial quantiles and has insignificant values.Furthermore, considering the habitat vulnerability (HAV) results, the impact of ECL, ECL 2 , and IND outcomes supports the GMM findings.Moreover, development expenditure (EXP) outcomes are inconsistent from the 75th to the 95th quantiles, as their values become significant.In addition, the trade openness and habitat vulnerability relation shows interesting outcomes, as it has a significant positive impact in initial quantiles, but from the 75th to the 95th quantiles, it becomes again significant with the opposite sign.As part of Europe's rapid development, the region's industry structure is now shifting.The export share of commodities is decreasing while the service share is increasing.Therefore, this shift in export structure corresponds to a reduction in climate vulnerabilities.However, for the case of non-European developed countries, trade openness (TRD) findings are inconsistent in the 05th to 25th quantiles and have an insignificant impact on HAV, but after that, TRD shows a significant effect on HAV.Additionally, considering the last model of health vulnerability (HEV), the impacts of energy cleanability gap (ECL) and ECL 2 on HEV resembles the GMM outcomes.However, the effects of EXP show some dissimilarity, especially the first quantiles showing significant impact; however, remaining quantiles are consistent with GMM outcomes in both European & other countries.The significant influence of the 75th-95th quantiles further demonstrates the heterogeneous effects of quantile outcomes of industrialization (IND), which is in line with previous mean regression analysis findings.However, it offers some significant and diverging effects on HAV.Furthermore, the quantile results of trade openness (TRD) also show some diversification from GMM outcomes.In particular, the TRD remains negligible in the initial three quantiles.Again, from the 75th quantile to the 95th quantile, TRD has a converging impact on HEV.Moreover, TRD results show consistency with GMM outcomes in the initial three quantiles.However, in the non-European countries panel, the 05th to 25th quantile results are contradictory to the main regression estimators.The latter result supports the findings of [29], where advanced countries are creating room for a converging impact and shifting their polluting industrial plants to low-income countries.

Discussion
Developed countries accounted for 60% of global GDP, with a low share of the population.In the 1990s, these economies accounted for over half of GHG emissions.In the literature, it has been agreed that fossil fuel energy is more responsible for environmental degradation.Subsequently, climate vulnerability leads to various occurrences, including droughts, soil erosion, floods, storms, and forest fires.Additionally, black carbon plays an important role in heat trapping, which raises temperatures.The environmental consequences that are being witnessed now are a direct result of human activities.However, the energy transition efforts of some European countries have highlighted the potential for climate improvement.In light of this, this study introduced the energy cleanability gap assessment and its implications on food, health, habitat, and ecosystems, adding to the body of new knowledge.The study is even more unique because it includes the clean energy gap rather than traditional energy sources and climate factors.Developed countries have made more progress towards the energy transition.Therefore, high-income countries have been taken into consideration for this study.The current study assessed the empirical influence of energy cleanability on climate vulnerabilities in this setting of energy transition.This study used it with other control factors, such as development spending, industrialization, and trade liberalization, to adopt strategies and solutions to combat climate change.
This study examined the relationships between the energy cleanability gap and climate vulnerabilities in European and non-European high-income countries from 2002 to 2019.This study delineates that European countries have initiated an energy transition process, and dependency on fossil energy has been reduced compared to non-European developed countries.In this view, European countries are shifting their economic infrastructure toward clean energy.In this regard, a small share of clean energy has a massive impact on environmental sustainability as European countries are more economically developed regions and are associated with more transportation, industrial production, and other running institutions that heavily rely on energy sources.Therefore, it has a converging impact on these climate vulnerabilities.Europe's rapid progress in the energy transition is also changing the dependence ratio.Moreover, it is an alarming situation for the Gulf countries as Europe's energy transition has put pressure on the Gulf to shift its reliance on fossil exports to renewables.In this regard [36], reports that the top three countries in the world rankings are Norway, Denmark, and Sweden.Only the United Kingdom and France appear in the top 10 largest economies in the world.Furthermore, European countries are leading the region in the energy transition.
However, the long-run energy cleanability gap's impact shows a clear warning as it negatively relates to climate vulnerability.This is because the energy transition process in several countries is relatively slow or not initiated, especially in golf countries.Hence, many institutions are not strategic in creating a better return on value from resources in the country.In this regard, oil-producing countries are energy-trading countries and require a significant decrease in their dependency on nonrenewable energy sources because it deteriorates sustainability and increases these vulnerabilities.In addition, as other non-European developed countries are starting a transition, some non-European countries' dependency on fossil exports will also hamper their current economic structure because the nature of jobs will also change, and they will face structural unemployment in the future.In particular, the United Arab Emirates, Saudi Arabia, Qatar, and Oman of the six-member Gulf Cooperation Council have recently launched renewable energy projects to achieve sustainability targets of zero carbon emissions.The increase in development expenditures has a converging effect on food and health vulnerabilities.Results from European high-income countries showed that development spending has been used for strategic environmental sustainability and reducing climate vulnerabilities.However, outcomes for non-European developed countries revealed that development expenditure had a diverging impact on ecosystem vulnerability.In this stance, such expenditure has positively impacted income sources, and it has changed the rural population's trend and shown a migration pattern toward urban areas for better living facilities [37].Therefore, this movement shifted higher human standards to material resources, and the results suggest that increasing development expenditure is increasing food and habitat threats.
In the case of other control variables, an increase in industrialization has raised ecosystem, food, and habitat vulnerabilities.These results indicated that the infrastructure has reduced vulnerabilities in the ecosystem, food, and health to different degrees in European countries.In particular, this study makes a more transparent analysis as the quantile outcomes revealed that from 2012 on, the advanced countries had created room for a converging impact by shifting their polluting industrial plants to low-income countries.However, non-European countries have contrasted as their industrialization process has increased ecosystem, food, and habitat vulnerabilities.In this regard, the study of [38] concluded that the industry value addition process further leads to the fast expansion of secondary industries and the existing structure of industries, providing significant evidence that these industries are based on fossil energy; however, this process increases climate vulnerabilities due to the vast consumption of unclean fuel.
Furthermore, this study finds a converging impact of trade openness on climate vulnerabilities in Europe.Trade openness has increased competitive mechanisms in production capacities by adopting the latest green technologies.So, these latest technologies have reduced ecosystem and food vulnerabilities.In addition, this study further revealed through the non-European panel that the impact of openness remains insignificant in terms of food, habitat, and health vulnerabilities.Considering these diverging roles, these countries have changed their policies and shifted their outdated industries to developing countries.However, mean regression and quantile outcome revealed that from 2009 onward, both European and non-European high-income countries had adopted the latest green energy-based trade and found a converging impact on climate vulnerabilities.

Conclusions and policy recommendations
This study examined the impact of the energy cleanability gap on climate or environmental vulnerabilities in 47 European and non-European high-income economies.The study constructed an energy cleanability gap via entropy weights and included its square to see if the relationship between clean energy and climate vulnerabilities is nonlinear.The study covered the period from 2002 to 2019.In terms of statistical tests, this study tested VIF and tolerance to see if there was any issue of multicollinearity.To evaluate the model, this study applied heteroskedasticity and autocorrelation tests, along with the test of endogeneity.For analyzing the relationship, the study uses fixed effects, random effects, GMM, and panel quantile techniques.
The study's findings can be summarized as follows: There is a U-shaped, nonlinear relationship between the energy cleanability gap and climate vulnerabilities.Specifically, the study found that when the energy cleanability gap increases, climate vulnerabilities decrease at first.However, after reaching a certain level, climate vulnerabilities start to decrease with an increasing energy cleanability gap.This is true for both European and non-European countries.Hence, this study proposes that access to clean cooking and renewable energy are the major factors that can drive down vulnerability and increase the economy's resilience.All of the vulnerabilities discussed can be handled more effectively by increasing the amount of clean energy in the economy.Development spending decreased food and health vulnerabilities in European nations while increasing ecosystem vulnerability and decreasing health vulnerability in non-European nations.Industrialization reduced the vulnerability of ecosystems, food, and habitat in Europe and increased ecosystem, habitat, and health vulnerability in non-European countries.In the case of trade openness, it was seen that it increased the security of the ecosystem and food sectors in Europe and that of food, habitat, and health systems in non-Europe but increased the insecurity of the ecosystem in non-Europe.For a comprehensive explanation, this study reported five quantiles (i.e., 5th, 25th, 50th, 75th, and 95th) during the PQR regression process.In particular, this regression process produces robust results, as their mean results support the GMM results.However, it also revealed various inconsistencies in quantitative results due to heterogeneity in the given data set.
Based on these results, several policy implications can be suggested.Since the energy cleanability gap implies a lack of clean energy in a country, and after reaching a threshold, it starts to increase climate vulnerabilities; it signifies the need to transition towards clean energy sources and away from fossil fuel sources.Both European and non-European countries should strive towards achieving carbon neutrality by investing in clean energy resources and thus addressing climate vulnerabilities.In this regard, public-private cooperation can play a significant role.The governments of these countries can provide subsidies to organizations that adopt clean energy sources.They should also implement low-carbon energy policies to speed up the advancement of renewable technologies.These policies will inspire breakthrough innovations and the industrialization of solar energy, wind energy, and bio-fuels.They should manage funds for clean energy via provisional agreements and establish short-term, medium-term, and long-term terms for the development of clean energy.Many countries are not adopting renewable technologies as they are costly compared to fossil fuel sources.Moreover, fossil fuel energy sources have longer-term subsidies available to them.Hence, policymakers need to consider the pricing policies which will help to disseminate renewable technologies.They should pursue green growth policies that will not only advance economic growth but also encourage sustainability.The study by [39] advocated that countries should adopt renewable energy to accelerate sustainability.Furthermore, attaining the SDG 9 objectives, which advocate for technological innovation, can help the attainment of both SDG 7 (e.g.clean energy) and SDG 13 (climate action).Therefore, the governments of these countries should invest in innovation and infrastructure.Particularly, countries are encouraged to adopt renewable energy sources that can help with resource efficiency and conservation in pursuit of a green economy [40].Low-carbon electricity generation has negative impacts on environmental vulnerabilities that can reduce fossil fuel adoption and carbon emissions.
Since development expenditures encourage climate security, governments of both European and non-European economies should increase development expenditures.Specifically, governments should reformulate their spending in such a way that it favors green growth.They should increase their spending on environmentally friendly projects and decrease their spending on pollution-related activities.For example, governments should not provide subsidies for non-renewable consumption; exploitation of timber, which can hurt the ecosystem; and tax holidays for firms that generate emissions should be completely removed.These can tackle environmental deterioration and, at the same time, reduce the fiscal burden on governments, which can increase spending on socially desirable products [41].Governments should also ensure that industrialization is in line with green growth policies for both groups.Moreover, the trade of low-carbon energy resources should be encouraged to conserve the climate and environment.
This study contains some limitations.For example, due to unavailable data, the study could not incorporate periods until 2022.Therefore, future research should incorporate the latest data as well as historical data to formulate climate sustainability policies for these countries.Although this study only looked at developed countries, developing countries do currently face significant challenges related to climate change.Therefore, future research should explore how the climate vulnerabilities of developing countries can be minimized through clean energy finance from developed economies.Since there are more countries in this study than in the data period, the study could not consider robust econometric techniques such as secondgeneration estimation techniques.Therefore, future research may also incorporate these techniques.

Table 3 . Estimation chart flow.
https://doi.org/10.1371/journal.pone.0297529.t003ecosystem, and health vulnerability compared to European high-income economies.The study next performs a multicollinearity test to determine the existence of multicollinearity issues in the model.The outcomes of VIF and tolerance values are presented in Table

Table 5 .
Multicollinearity tests.tests are employed to determine heteroskedasticity and autocorrelation.The modified Wald test investigates the model heteroskedasticity characteristics for this purpose.The results of the Wald test demonstrate that the chosen panel is distorted.However, problems with heteroskedasticity make estimation less accurate, rendering first-generation regression approaches useless.Secondly, the autocorrelation test used in this study is based on residuals.